1. Field of the Invention
The present invention relates to a siloxane-based resin and an interlayer insulating film for a semiconductor device formed using the same. More specifically, the present invention relates to a siloxane-based resin having a novel structure and a resinous film useful as an insulating film disposed between interconnect layers of a semiconductor device.
2. Description of the Related Art
As the circuit density of multilevel integrated circuit devices increases, the size of a semiconductor device is constantly required to be reduced. The chief obstacle to the size reduction of the semiconductor device is the R(resistance)×C(capacitance) delay due to crosstalk between interconnect layers. A solution to this problem is to lower the dielectric constant of interlayer insulating films so as to decrease the R×C delay as much as possible. Accordingly, there have been various attempts to provide an insulating film having a low dielectric constant.
Conventionally, in the field of semiconductor devices, interlayer insulating films have been formed by a CVD(chemical vapor deposition) method using SiO2 having a dielectric constant of 4.0. However, U.S. Pat. Nos. 3,615,272; 4,399,266; 4,756,977 and 4,999,397 disclose the formation of insulating films by a SOD(spin on deposition) method using polysilsesquioxanes having a dielectric constant of 2.5–3.1 as well as good planarization properties.
Polysilsesquioxanes as well as preparation methods thereof are well known in the art. For example, U.S. Pat. No. 3,615,272 discloses a method of preparing a completely condensed, soluble hydrogensilsesquioxane resin, which comprises the steps of condensing trichlorosilanes in a sulfuric acid medium and washing the resulting resin with water or aqueous sulfuric acid. Also, U.S. Pat. No. 5,010,159 discloses a method of synthesizing a soluble condensed hydridosilicon resin, which comprises the steps of hydrolyzing hydridosilanes in an arylsulfuric acid hydrate-containing a hydrolysis medium and contacting the resulting resin with a neutralizing agent. U.S. Pat. No. 6,232,424 describes a highly soluble silicon resin composition having excellent solution stability, which is prepared by hydrolyzing and polycondensing tetraalkoxysilane, organosilane and organotrialkoxysilane monomers in the presence of water and a catalyst. U.S. Pat. No. 6,000,339 describes that a silica-based compound is useful for improving the resistance to oxygen plasma and improving physical properties as well as the thickness of a coating film, which can be obtained by reacting a monomer selected from the group consisting of alkoxysilane, fluorine-containing alkoxysilane and alkylalkoxysilane with a titanium- or zirconium-alkoxide compound in the presence of water and a catalyst. U.S. Pat. No. 5,853,808 describes that siloxane and silsesquioxane polymers useful for forming SiO2-rich ceramic coating can be obtained from hydrolysis and polycondensation of organosilanes having a β-substituted alkyl group. Meanwhile, EP 0 997 497 A1 discloses that hydrolyzation and polycondensation of a certain combination of alkoxysilanes including mono-, di-, tri-, tetraalkoxysilane and trialkoxysilane dimers can provide resinous materials for insulating films.